hashCode或equals方法中的HibernateException

Question

hashCode或equals方法中的HibernateException

spring-boothibernatejpahashcodelazy-initialization

10

我正在使用Spring和Hibernate。在没有实现equals和hashCode的情况下进行提取时，一切都正常。当我添加这两种方法并执行查询时，在hashCode内部抛出了Lazyinitializationexception异常。我认为这是因为Hibernate在获取集合之前尝试填充A的集合并调用hashCode，但这只是我的假设，如果有人能给我提示，我会非常感激。 ---------------- 在Repository中 ----------------

@Query(value = "select u from User u " +
            "left join fetch u.companies c " +
            "left join fetch c.garages g " +
            "left join fetch g.parkingSpaces pk " +
            "left join fetch u.roles r")
    Set<User> findAllUsers();

---------------- 服务中 ----------------

@Transactional(readOnly = true)
    public Set<User> findAllUsers() {
        return userRepository.findAllUsers();
    }

---------------- 在用户中 ----------------

    @ManyToMany
    @JoinTable(
            name = "users_companies",
            joinColumns = @JoinColumn(name = "users_id", nullable = false, referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "companies_id", nullable = false, referencedColumnName = "id")
    )
    private Set<Company> companies;

@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(email, user.email) &&
                Objects.equals(companies, user.companies) &&
                Objects.equals(roles, user.roles) &&
                Objects.equals(vehicles, user.vehicles);
    }

    @Override
    public int hashCode() {
        return Objects.hash(email, companies, roles, vehicles);
    }

---------------- 在公司中 ----------------

@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Company company = (Company) o;
        return Objects.equals(name, company.name) &&
                Objects.equals(garages, company.garages) &&
                Objects.equals(images, company.images);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, garages, images);
    }

    @OneToMany(mappedBy = "company", orphanRemoval = true)
    private Set<Garage> garages;

以下是堆栈跟踪：

2020-12-04 17:14:18.500 ERROR 6416 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[.[dispatcherServlet]      : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: collection was evicted; nested exception is org.hibernate.HibernateException: collection was evicted] with root cause

org.hibernate.HibernateException: collection was evicted
    at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:43) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2164) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:589) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:264) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:585) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:149) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.collection.internal.PersistentSet.hashCode(PersistentSet.java:458) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at java.util.Arrays.hashCode(Arrays.java:4685) ~[?:?]
    at java.util.Objects.hash(Objects.java:146) ~[?:?]
    at com.parkeasy.company.Company.hashCode(Company.java:98) ~[classes/:?]
    at java.util.HashMap.hash(HashMap.java:339) ~[?:?]
    at java.util.HashMap.put(HashMap.java:607) ~[?:?]
    at java.util.HashSet.add(HashSet.java:220) ~[?:?]
    at java.util.AbstractCollection.addAll(AbstractCollection.java:352) ~[?:?]
    at org.hibernate.collection.internal.PersistentSet.endRead(PersistentSet.java:355) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:239) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:224) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.engine.loading.internal.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:198) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.endCollectionLoad(Loader.java:1293) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1240) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.processResultSet(Loader.java:1006) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.doQuery(Loader.java:964) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:350) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2887) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.doList(Loader.java:2869) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2701) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.Loader.list(Loader.java:2696) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:506) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:400) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:219) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1415) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1565) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1533) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.hibernate.query.Query.getResultList(Query.java:165) ~[hibernate-core-5.4.21.Final.jar:5.4.21.Final]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$CollectionExecution.doExecute(JpaQueryExecution.java:126) ~[spring-data-jpa-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:88) ~[spring-data-jpa-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:154) ~[spring-data-jpa-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:142) ~[spring-data-jpa-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor$QueryMethodInvoker.invoke(QueryExecutorMethodInterceptor.java:195) ~[spring-data-commons-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152) ~[spring-data-commons-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130) ~[spring-data-commons-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) ~[spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:149) ~[spring-data-jpa-2.3.4.RELEASE.jar:2.3.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at com.parkeasy.user.$Proxy162.findAllUsers(Unknown Source) ~[?:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
    at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at com.parkeasy.user.$Proxy102.findAllUsers(Unknown Source) ~[?:?]
    at com.parkeasy.user.UserService.findAllUsers(UserService.java:89) ~[classes/:?]
    at com.parkeasy.user.UserService$$FastClassBySpringCGLIB$$302b133c.invoke(<generated>) ~[classes/:?]
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:771) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) ~[spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:749) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:691) ~[spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at com.parkeasy.user.UserService$$EnhancerBySpringCGLIB$$e8d727f.findAllUsers(<generated>) ~[classes/:?]
    at com.parkeasy.user.UserController.details(UserController.java:40) ~[classes/:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
    at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.springframework.web.filter.AbstractRequestLoggingFilter.doFilterInternal(AbstractRequestLoggingFilter.java:289) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:204) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.3.4.RELEASE.jar:5.3.4.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.38.jar:9.0.38]
    at java.lang.Thread.run(Thread.java:834) [?:?]

- Alexander Mladzhov

尝试在较小的事务中预取数据或扩展事务边界。后者不推荐，并且应该在投入生产环境之前进行调优。 - Tushar

你能发布异常堆栈跟踪吗？ - Madhusudana Reddy Sunnapu

3个回答

3

为了避免在hashCode()或equals()方法中出现LazyInitializationException，请不要在对象内部调用任何集合。阅读下面的原因，了解这种实现具有恒定哈希码和仅依赖于主键的相等性方法。

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (!(o instanceof User)) return false;
    User user = (User) o;
    return id != null && id.equals(user.getId());
}

@Override
public int hashCode() {
    return 24;
}

上面的示例是针对类 User 的，并假设主键称为 id，并且作为类(而不是基本数据类型)实现以获取正确的null值。这篇博客文章很好地解释了为什么可以和应该使用这种奇怪的实现。

理由

equals() 和 hashCode() 必须返回相等的值，对于同一个对象，它必须在所有可能的 JPA 阶段中等于自身。每个类的每个实体都有一个唯一且一致的属性(因为它不能被更改)，即数据库键。

唯一的问题在于瞬态状态，即在实体持久化之前。但是，在将对象持久化之前，只有引用相等的对象才能被视为相等的对象。如果这些对象被持久化，很明显每个主键只会引用类/表中的一个实体。

根据这个论据，主键形成了equals()方法的适当业务键。但是，当主键在函数hashCode()中使用时，并且在将对象存储在例如Set中之前，哈希码会在持久化对象时更改，因此Set将不再起作用。让 equals()返回true的hashCode()的方法不能依赖于主键。

根据下面的论点，这种实现破坏了像HashMap和HashSet这样的结构的性能优势。 "然而，出于性能原因，您应该始终限制存储在集合中的实体数量。" 数据库端的性能惩罚比仅使用单个桶要高得多。

- Felix Seifert

为了提高效率，最好使用固定的哈希码。你建议的实现是可能最低效的实现。这会将基于哈希的集合（O(1)）转换为列表（O(n)）。此外，OP没有LazyInitializationException。 - Stanislav Bashkyrtsev

我添加了一个解释，说明为什么这样的实现是可以的。 - Felix Seifert

这个实现是不行的。如果你不想正确地实现hashCode，那么为什么要使用基于哈希的集合呢？使用列表更安全。我已经在你提到的文章中发表了评论，但它正在等待审核。在大多数情况下，你应该简单地不要为实体实现equals/hashCode。只有值对象需要这些方法 - 不是实体。 - Stanislav Bashkyrtsev

这种论证是有道理的。然而，hashCode() 函数的基本实现只是为内存地址生成一个 int。因此，一个数据库实体是否需要一个重写的哈希函数（和因此也需要一个重写的 equals() 函数）来符合 JPA 原则？ - Felix Seifert

是的，使用JPA时，equals()和hashCode()都不是必需的。 - Stanislav Bashkyrtsev

顺带一提，默认的hashCode()并不一定是内存地址，似乎大部分时候它只是在对象创建时生成的随机数，至少在OpenJDK中是这样的：https://srvaroa.github.io/jvm/java/openjdk/biased-locking/2017/01/30/hashCode.html - Stanislav Bashkyrtsev

1

首先，您查询中的left join B b left join C c left join D d部分实际上除了用冗余的JOIN影响查询性能外没有任何作用。您可能想使用JOIN FETCH代替。然而，请在随处添加FETCH之前先阅读this question。

其次，如果您的hashCode（或其他任何方法）尝试在未打开持久性上下文的情况下访问懒加载的集合，则会出现LazyInitializationException。解决方案是不要让您的方法这样做。

编辑：您是否碰巧使用了二级缓存？我不能确定它是否有所帮助，因为我链接到的答案指出，不支持嵌套的FETCH JOIN，但请尝试将cascade = DETACH添加到所有急切获取的关联中。

- crizzis

我在这里编写查询时忘记添加fetch了，但在项目中已经有了fetch。 - Alexander Mladzhov

尝试在未打开持久性上下文的情况下访问懒加载集合 - 但实际情况并非如此，请仔细查看堆栈跟踪。 - Stanislav Bashkyrtsev

@StanislavBashkyrtsev 自此回答发布以来，问题细节已经发生了变化。 - crizzis

我理解了。 - Stanislav Bashkyrtsev

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- Stanislav Bashkyrtsev · Accepted Answer

那是一个有趣的问题（bug）你遇到了。请注意它并不是一个LazyInitializationException异常:

org.hibernate.HibernateException: collection was evicted

如果由于使用了 join fetch，您在深度上加载2个以上的集合并且使用 HashSet/hashCode，则会出现此问题。Hibernate 知道它必须获取 Company#garages 的内部集合，但在调用 Company#hashCode（这是由于 HashSet 在 Hibernate 内部代码中发生）时 - 它还没有执行此操作。因此，当请求该集合时，它应该已经被加载，但实际上却不存在，这可能被称为错误，尽管我不会为此创建一个工单 - 我更愿意更改代码。

在 equals/hashCode 中迭代其他实体是低效的，并且会导致更多的错误。这些方法应使用不可变字段，即使使用 id 也可能在持久化过程中出现问题（标识和序列策略）。

您可以完全跳过实体的 equals/hashCode 方法，因为 ORM 将确保只有通过 Session/EntityManager 加载了 1 个实例。这意味着引用将始终相同，因此默认的 hashCode 将正常工作。

equals/hashCode 对于值对象很重要（它们不存储在数据库中），但对于实体来说，摆脱它们更安全。